In the error log (./apache/logs/error.log) I found the following line Parent: child process exited with status 3221225477 -- Restarting. After a long search on the Internet I found this thread which solves the problem for me. The only thing I had to do was download this package and replace the libmysql.dll file in the apache/php and /php folder with the one in the zip.) Software used: XAMP 1.7.0 / Vista 32 bit / Zend 1.7.4.